1. Field of the Invention
The present invention relates to processing an input image that contains a plurality of objects.
2. Description of the Related Art
In order to properly output an output image to a printer or display device according to image data, it is necessary to perform color processing including color correction, color conversion, and binary coding on each of a plurality of objects constituting an output image according to a type of object. In general, for printing out or displaying an image created by a computer application, a device driver or a device translates a set of rendering instructions sent from the application into an image for a whole page that is represented by image data. The image is then printed out or displayed.
A set of rendering instructions constitutes a document. Among the rendering instructions issued to a device driver.
An image rendering instruction specifies rendering of a photographic picture. A text rendering instruction specifies rendering of a text. A graphic rendering instruction specifies rendering of a graphic. The device driver performs color processing suitable for an object according to an instruction, converts the resultant object into an image capable of being output from an output device, and outputs the image.
In recent years, a color management system permitting color processing optimal for each device, such as, ICM for the Microsoft Windows™ or ColorSync™ released from Apple Inc. has been installed in many computer systems.
However, even when such a color management system is installed, if an original photographic image is of very poor quality, a high-quality, high-definition output cannot naturally be provided. For example, when an image is produced using digital cameras, which have become popular in recent years, if the exposure is improper, the image having an improper exposure is printed with the improper exposure. An excellent output cannot be provided. To overcome this problem, a user may use image retouch software or the like to perform image correction such as nonlinear color balancing on the whole original image.
However, when a user who lacks expertise and experience on image correction attempts to correct an image, the process can be very frustrating and time consuming.
Assume that a document for desktop publishing (DTP) is an existing document that contains an original image to which a photograph that has not been corrected is pasted. In order to correct only the photograph in the original image, a complex task must be carried out. Specifically, the photograph in the original image must be designated and cut out, and then corrected using image retouch software. The resultant photograph is then pasted again to the original image.
For overcoming the aforesaid disadvantages, U.S. patent Ser. No. 09/336,987 filed on Jun. 11th, 1999 by an applicant, describes a process for automatically correcting object images of a predetermined type contained in an input image according to a color distribution.
In that application, a printer driver issues a request for print data (a set of rendering instructions), which specifies rendering of an image for a print page, twice to an application or an operating system (OS).
In the first print data processing flow, print data is analyzed in order to acquire information needed for image correction, that is, preparations are made for execution of image correction.
In the second print data processing flow, the result of acquisition performed in preparation for execution of image correction is used to correct part of the image rendering instructions that have been judged to be corrected. Color matching is executed, and the rendering instructions are translated into raster image data and the raster image data is developed into a page memory. A print image is then produced and transferred to a printer.
However, the number of data items per page has increased drastically partly because applications offer advanced performance. If every data is requested twice, a print start time instant is delayed by a time required for issuance of a first request and response to the first request. This greatly affects an image output speed. In particular, a request must be issued twice even for a page that contains no image. The decrease in the speed is undesired.